Life Zone LA Site Form Biotic Community
Barren or Sparsely Vegetated  grassland

TM-3. Sparse Grassland (Alkali Sacaton); barren disturbed ground
TM-2. Sparse Grassland (Black Grama or Galleta); barren disturbed ground

Open alluvial flats of basin bottoms (1,430 - 1,550 m; 4,700-5,090 ft) that are either barren or sparsely vegetated with alkali sacaton (Sporobolus airoides) and burrograss (Scleropogon brevifolius), or are barren hills (badlands).
grassland grassland
desert desert scrubland
chaparral scrubland
oak woodland woodland Woodlands generally include evergreen oak and conifer species that occupy certain areas along an elevational gradient from low-elevation desert shrub/grasslands and short-grass prairies to high-elevation montane coniferous forests of ponderosa pine and Gambel oak. Oak woodlands occur within the range of 4,000– to 9,000–feet elevation. Gambel oak occurs at higher elevations, and wavyleaf oak (Quercus undulata) occurs either below Gambel oak or intermingled with it in a transition zone. Woodlands were used extensively by prehistoric and historic populations for habitation and subsistence. Uses today include grazing, fuelwood harvest, and recreation.
evergreen oak woodland woodland Madrean evergreen woodland  Evergreen oak woodland, characterized by wet summers and mild winters, extends from the Sierra Madre of Mexico into southeastern Arizona and southwestern New Mexico. In the United States, a variety of oak species such as Emory oak (Quercus emoryi), Arizona white oak (Q. arizonica), Mexican blue oak (Q. oblongifolia), gray oak (Q. grisea), silverleaf oak (Q. hypoleucoides), and netleaf oak (Q. rugosa) are found in conjunction with the following Madrean pine species–Apache pine (Pinus engelmannii), Chihuahua pine (P. leiophylla var. chihuahuana), and Arizona pine (P. arizonica) (Brown 1994).
Great Basin conifer woodland  Piñons and junipers, together or alone, dominate coniferous woodland communities. These woodlands occupy approximately 23 million acres in New Mexico, about 13 percent of which are on national forest lands, and 4.1 million acres in Arizona, 34 percent on national forest lands. The piñons include Pinus edulis, the most common piñon pine throughout the type, border piñon (P. discolor), and Arizona singleleaf piñon (P. californarium subsp. fallax). Junipers are frequently found at lower elevations than piñons and typically occupy sites with deep soils. The most common junipers in the Southwest are one-seed juniper (Juniperus monosperma) found in central and southern New Mexico and much of Arizona below the Mogollon Rim, the Rocky Mountain juniper (J. scopulorum) in the higher and colder woodlands of northern New Mexico and Arizona, Utah juniper (J. osteosperma) in northwestern New Mexico and northern Arizona, and alligator juniper (J. deppeana) associated with the Madrean woodlands of southern Arizona and New Mexico (Brown 1994, Gottfried 1992).
coniferous woodland woodland

TM-23. Oneseed Juniper Woodland Savanna; Inclusion: Blue Grama Grassland

TM-26. Oneseed Juniper Woodland, or Shrub Live Oak Shrubland, or Black Grama or Blue Grama Grasslands

TM-28. Oneseed Juniper Woodland, or Shrub Live Oak Shrubland

TM-21. Oneseed Juniper Woodland (in part, see No.9)

 Rocky Mountain Conifer Savanna (Oneseed Juniper Woodlands) 

Very open woodlands of lower elevation foothills, escarpments, and piedmonts (bajadas) and alluvial fans (1,550-2,100m; 5,100-6,900 ft). Stands are characterized by scattered, low-statured oneseed juniper (Juniperus monosperma) trees with the grassy inter-tree spaces dominated by grama grasses (Bouteloua gracilis, B. hirsuta, B. eriopoda, and B. curtipendula). Pinyon pines (Pinus edulis) are sub-dominant or absent. Stands are often intermixed at the lower elevations with patches of Blue or Black Grama Grasslands, and Shrub Live Oak Shrublands at higher elevations. Shrub live oak stands are particularly prominent on escarpment slopes of the Los Pinos Mountains. Diversity can be moderately high, and common associates are the shrubs banana yucca (Yucca bacata), broom snakeweed (Gutierrezia sarothrae), tree cholla (Opuntia imbricata), and tulip pricklypear (O. phaeacantha); the grasses New Mexico needlegrass (Stipa neomexicana), galleta (Hilaria jamesii) and purple threeawn (Aristida purpurea); and a wide variety of forbs such as plains blackfoot (Melapodium leucanthum) and zinnia (Zinnia grandiflora).

grassy inter-tree spaces dominated by grama grasses (Bouteloua gracilis, B. hirsuta, B. eriopoda, and B. curtipendula). 
coniferous woodland woodland

TM-27. Pinyon or Oneseed Juniper Woodlands; Inclusions of Mountain Mahogany Shrubland and Sideoats Grama Grassland

TM-31. Pinyon Woodland
Rocky Mountain Conifer Savanna (Oneseed Juniper Woodlands) 

Open to moderately closed woodlands dominated by low-statured pinyon pine (Pinus edulis) with oneseed juniper (Juniperus monosperma) as sub-dominant associate. These woodlands are associated with moderate to steep slopes of the highest elevations of the Los Pinos and Ladrones Mountains (1,850-2,300; 6,050-7,550 ft). Near the summit of the Ladrones there are small inclusions of Ponderosa Pine (Pinus ponderosa var. scopulorum) Woodland.

Understories are a mixture of shrubs and scattered grasses and forbs. Shrub live oak (Quercus turbinella), mountain mahogany (Cercocarpus montanus), banana yucca (Yucca bacata) and sacuahista (Nolinia microcarpa) are often well represented to abundant. Sideoats grama (Bouteloua curtipendula), blue grama (B. gracilis), and wolfstail (Lycurus phleoides) are the most common grasses. Forb diversity can be moderate to high; ragleaf bahia (Bahia dissecta), false pennyroyal (Hedeoma nana) and Fendler's sandmat (Chamaesyce fendleri) are common. Inclusions of mountain mahogany stands occur on rugged escarpment slopes and commonly on sites that have been burned. 
ponderosa pine forest Rocky Mountain/Madrean montane coniferous forest  Ponderosa pine (yellow pine or blackjack pine) is found from 6,500 to 8,000 feet elevation. At lower elevations, the ponderosa pine forest meets woodlands and at higher elevations transitions into the mixed conifer zone. Ponderosa pine forests of central and northern New Mexico and Arizona cover about 8.4 million acres. The predominant form throughout the Southwest is the three-needled, Rocky Mountain ponderosa pine (P. ponderosa var. scopulorum). In lower elevations of southern Arizona, however, the five-needled, Arizona pine is more common. Other species associated with ponderosa pine at low elevations are Gambel oak and New Mexico locust (Robina neomexicana); at high elevations associates are southwestern white pine (Pinus strobiformis), Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca), Rocky Mountain white fir (Abies concolor var. concolor), and quaking aspen (Populus tremuloides) (Brown 1994). Uses include timber harvest, grazing, camping, and other types of recreation offering cool relief from hot urban areas.
mixed conifer forest Rocky Mountain/Madrean montane coniferous forest  Mixed conifer forests dominated by Douglas-fir, white fir, and blue spruce (Picea pungens) occur at elevations from 8,000 to 9,500 feet. There are about 1.5 million acres of mixed conifer forest in the Rocky Mountain and Madrean montane forests of southern Colorado, New Mexico, Arizona, and the Sierra Madre Occidental of Mexico (Brown 1994). Ponderosa pine, southwestern white pine, aspen, and a number of other tree species may occur in these forests. Uses are similar to the ponderosa pine community.
spruce–fir forest Rocky Mountain subalpine coniferous forest Spruce–fir forests are found at high, subalpine, elevations in the Southwest from approximately 8,000 feet to over 12,000 feet. Spruce–fir forests are typically restricted to areas receiving more than 25 inches of precipitation from winter snows and summer thunderstorms. The predominant spruce is Engelmann spruce which is found as far south as the Pinaleno Mountains in Arizona and the Sacramentos in New Mexico. The co-dominant species is subalpine fir (Abies lasiocarpa). Some populations of subalpine fir possess a distinctive outer cortex and are called corkbark fir (A. lasiocarpa var. arizonica). Small stands of aspen or blue spruce are found within the spruce–fir forest (Brown 1994). Uses include wilderness recreation, skiing, and the enjoyment of high places. Mountain peaks have special cultural and religious significance for many Southwestern Indian tribes.
Quaking aspen occurs at elevations above 6,000 feet as small, transient patches in ponderosa pine, mixed conifer, or spruce–fir forests. There are close to 500,000 acres of aspen in the Southwest, seventy-five percent in northern New Mexico and the remainder in the Mogollon Rim-White Mountains of Arizona (Brown 1994). Aspens can reproduce by cloning from an established root system and establish a new stand of trees quickly after a fire or other disturbance. Aspens, however, are intolerant of shade and eventually lose out to competition when they become overtopped by re-invading conifers. Aspen stands are especially valued for their scenic quality and use by traditional communities.
tundra
riparian wetlands marshland Fremont cottonwood (Populus fremontii

narrowleaf cottonwood (P. augustifolia)

 Rio Grande Cottonwood (Populus deltoides var. wislizeni

Riparian wetlands including cienegas make up less than 2 percent of the land of New Mexico and Arizona, but they are the most biologically diverse and productive ecosystems in the Southwest. Over 65 percent of Southwestern animals depend on riparian habitats during all or part of their life cycles. Millions of Southwestern residents use these areas for recreation and agriculture. The most important species of Southwestern riparian wetlands are the Fremont cottonwood (Populus fremontii) and the narrowleaf cottonwood (P. augustifolia) (Brown 1994).
 alkali sacaton (Sporobolus airoides), inland saltgrass (Distichlis spicata) or vine mesquite grass (Panicum obtusum), to dense, shrub-like stands of the introduced salt cedar (Tamarix ramosissima) with little or no understory.

The General Ecosystem Survey (Carleton et al. 1991) groups Southwestern ecosystems into life zones characterized by biotic community types including desert, grassland, chaparral, evergreen oak woodland, coniferous woodland, ponderosa pine, mixed conifer, spruce–fir, tundra, and riparian wetlands. Because this an assessment of forest, woodland, and associated riparian ecosystems, desert, grassland, chaparral, and tundra life zones are excluded from further discussion. The concept of a life zone is derived from a taxonomic classification system described first by Merriam (1898), revised by UNESCO (1973), and applied in the Southwest by the Terrestrial Ecosystem Survey. The General Ecosystem Survey life zones (Table 2.2) can be cross-referenced to the biotic communities described by Brown and Lowe (1977, 1980) and Brown (1994). Aspen is a component of the montane forest found mostly in the mixed conifer zone but also in the ponderosa pine and the spruce–fir zones.

Brown, D.E. 1994. Biotic communities: southwestern United States and northwestern Mexico. Salt Lake City, UT: University of Utah Press. 342 p. literature cited

Brown, D.E.; Lowe, C.H. 1977. Biotic communities of the Southwest. General Technical Report RM–41. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Range and Experiment Station.

Brown, D.E.; Lowe, C.H. 1980. Biotic communities of the Southwest. General Technical Report RM–78. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Range and Experiment Station.

Carleton, J.O.; Robbie, W.A.; Robertson, G.T.; Spann, C.L.; Brown, H.G., III; Gass, J.; Shaw, D.W.; Robison, T.; Moir, W.H.; Potter, D.; Fletcher, R.A.; Galeano-Popp, R.; Miller, G.J. 1991. General ecosystem survey. Albuquerque, NM: U.S. Department of Agriculture, Forest Service, Southwestern Region. 188 p. plus maps.

Gottfried, G.J. 1992. Ecology and management of the Southwestern pinyon-juniper woodlands. Ffolliott, P.F.; Gottfried, G.J.; Bennett, D.A.; Hernandez C., V.M.; Ortega-Rubio, A.; Hamre, R.H., tech. coords., Ecology and management of oak and associated woodlands: perspectives in the southwestern United States and northern Mexico; 1992 April 27–30; Sierra Vista, AZ. General Technical Report RM–218. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station.

Merriam, C.H. 1898. Life–zones and crop zones of the United States. Bulletin 10. Washington, DC: U.S. Department of Agriculture, Division of Biological Survey. 79 p.

United Nations Educational, Scientific and Cultural Organization (UNESCO). 1973. International classification and mapping of vegetation; Series 6, Ecology and Conservation. Paris. 93 p.

 

Cienega: a Southwestern, non-forested wetland. Cienegas are dominated by graminoids and may be seasonally dry.glossary

Forb: an herbaceous plant other than a graminoid.glossary

Graminoid: a grass or grass-like plant.glossary

Woodland: an area or biotic community dominated by widely-spaced trees of short stature growing on warm, dry sites. In the Southwest, common woodland species are oak, pinyon, and juniper; these woodlands usually occur below 8,000 feet elevation.glossary

The life zones that Merriam identified, along with characteristic plants, are as follows:

The Canadian and Hudsonian life zones are commonly combined into a Boreal life zone.

This system has been criticized as being too imprecise. For example, the scrub oak chaparral in Arizona shares relatively few plant and animal species with the Great Basin sagebrush desert, yet both are classified as Upper Sonoran. However it is still sometimes referred to by biologists working in the western United States. Much more detailed and empirically based classifications of vegetation and life zones now exist for most areas of the world.

Life zone - Wikipedia, the free encyclopedia

 

Merriam's Life Zones 1891
Modern Vegetation Zones
Elevation
Range (feet)
Annual
Precipitation
Arctic-Alpine
Alpine Tundra
11,500-12,700
35"-40"
Hudsonian
Spruce-Fir or Subalpine Conifer Forest
9,500-11,500
30"-40"
Canadian
Mixed Conifer Forest
8,000-9500
25"-30"
Transition
Ponderosa Pine Forest
6000-8500
18"-26"
Upper Sonoran
Pinyon-Juniper Woodland, Semi-Arid Grasslands, Semi-Arid Scrub
3500-6500
10"-20"
Lower Sonoran
Mojave, Sonoran, or Chihuahuan Desert
100-3500
3"-12"

References:

Merriam, C. H. and Steineger, L. 1890. Results of a biological survey of the San Francisco mountain region and the desert of the Little Colorado, Arizona. North American Fauna Report 3. U.S. Department of Agriculture, Division of Ornithology and Mammalia, Washington, D.C., 136 pp.

Phillips, Arthur M. III, House, Dorothy A., and Phillips, Barbara G. 1989. Expedition to the San Francisco Peaks: C. Hart Merriam and the Life Zone Concept. Museum of Northern Arizona Plateau 60: 19-30.

Sterling, K. B. 1974. The Last of the Naturalists-The Career of C. Hart Merriam. Arno Press, New York, NY.

C. Hart Merriam and the Life Zones Concept

Semi-arid Grasslands and Shrublands

Great Basin grassland type

Grassland north of Flagstaff, AZ. Photo by John Grahame

Below 6,000 feet in the cool-temperate region of southern Utah, northern Arizona, and northwestern New Mexico several different types of native grasslands were once common. The two most dominant were a Great Basin grassland, typical of the more western, central, and northern regions, and a Plains grassland, which is confined to the southeastern part of the region. Plains grasslands are commonly dominated by Blue Grama or other gramas that extend into the area from southern Colorado and northwestern Texas. Great Basin grasslands are dominated by Galleta Grass and Indian Rice Grass and reach down to the Colorado Plateau from the northwest. Both types intergrade downslope with semi-arid scrub communities and upslope with pinyon-juniper woodlands.

A large transitional area between the two types occurs in north-central Arizona and extreme southern Utah. Most of the cold-tolerant, cool-season bunch grasses that are native to these grasslands are most productive during spring and early summer, and once existed in a mosaic with deep-rooted shrubs. Until the late 1800s and the coming of the railroad and the cattle industry, the only large animals to graze these lands were pronghorn antelope. It took only 10-15 years of overgrazing by cattle near the end of the last century to extensively alter these ecosystems. The native bunchgrasses, not generally tolerant of grazing, sustained high mortality when grazed heavily in spring. Wildfires, once common in these grasslands, are far less frequent today as grazing has left less residual grass to carry fires and land management agencies maintain fire suppression policies. Both grazing and fire suppression favored shrub species over grasses and accelerated soil erosion. Site conditions have been permanently altered, and Eurasian annual grass species such as cheatgrass have aggressively colonized vast areas.

No visitor to these cold-temperate regions can fail to be impressed by the omnipresence of big sagebrush, a hardy, cold-tolerant shrub that shapes the ecosystems it dominates. Its expansion on the Colorado Plateau has been remarkable. Though big sagebrush tends to be widely spaced with herbaceous plants and grasses living beneath them, the intershrub spaces are barren or contain microphytic crusts composed of lichens and algae. The shrubs concentrate water and nutrients to form islands of fertility that are not easily altered. The current mosaic of shrublands dominated by big sagebrush, and grasslands dominated by cheatgrass, is in large part a reflection of continuing desertification of the Colorado Plateau. The pre-settlement mosaic of cool-season bunch grasses and deep-rooted shrubs may now be one of the rarest ecosystems in the Southwest.

Grazing continues to be widespread in these grasslands, and the colonization by cheatgrass and expansion of big sagebrush at the expense of native perennial grasses is expected to continue. Extensive amounts of land are also being converted to agricultural production, especially in the Four Corners area where Arizona, Colorado, New Mexico and Utah meet. Once these ecosystems are converted, there is only limited potential for conversion to native grasslands, either mechanically or by removal of livestock.

Semi-arid Grasslands and Shrublands of the Colorado Plateau

Biotic Communities

Alpine Tundra
Subalpine Conifer Forest
Quaking Aspen Forest
Mixed Conifer Forest
Ponderosa Pine Forest
Montane Chaparral/Scrub
Pinyon-Juniper Woodland
Mountain Grasslands
Semi-arid Grasslands
Mountain Wetlands
Riparian Areas
Paleocommunities
Elevational Range
Merriam's Life Zones

Biotic Communities of the Colorado Plateau

Lower Sonoran Life Zone. This vegetation of this life zone corresponds with the hot deserts of the southwestern United States and northwest Mexico (the Mojave, Sonoran, and Chihuahuan deserts). Creosotebush (Larrea tridentata) and other desert shrubs and succulents occur at elevations from 100 ft to 3,500-4,000 ft above sea level. Total annual precipitation averages 10 inches or less.


Upper Sonoran Life Zone.A number of communities are characteristic of this zone that ranges from 3,500-4,000 ft to about 7,000 ft in elevation. These include a woodlands of evergreen oaks (Quercus spp.), pinyon pine (Pinus cembroides), and/or juniper (Juniperus spp.); the Arizona chaparral of leathery-leaved scrub oaks (e.g., Quercus emoryi), manzanita (Arctostaphylos spp.), buckthorn (Rhamnus spp.) and mountain mahogany (Cercocarpus spp.); grassland; and Great Basin desertscrub with its dominant sagebrush (Artemsia tridentata). Total annual precipitation varies from 8 to slightly more than 20 inches.


Transition Life Zone. An open ponderosa pine (Pinus ponderosa) forest is characteristic at elevations from 6,000 to 9,000 ft. Total annual precipitation ranges from 18 to 26 inches.


Canadian Life Zone. The fir forest of this life zone is dominated by Douglas fir (Pseudotsuga menziesi). White fir (Abies concolor) is also characteristic. In some places pines (other than Ponderosa) are also common. Deciduous broadleaf trees such as Gambel oak (Quercus gambeli), and quaking aspen (Populus tremuloides) can also be found here. The elevation of the Canadian zone in Arizona ranges from 7,500-8,000 ft to 9,000-9,500 ft; and precipitation from 25 to 30 inches.


Hudsonian Life Zone. A spruce-alpine fir community is found in this life-zone. Common species include Engelmann spruce (Picea engelmanni), blue spruce (P. glauca), Alpine fir (Abies lasiocarpa) and bristlecone pine (Pinus aristata). Trees decline in height from roughly 80 feet to dwarfed, gnarled individuals deformed by the wind near timberline (the Krummholz). The Hudsonian zone varies from 8,000-9,000 ft. to 11,500 feet and receives 30 to 35 inches of precipitation a year.


Arctic-Alpine Life Zone. Occurring above treeline, this life zone corresponds to the Arctic tundra. Two main habitat types are found on the wind-swept peaks of the highest mountains: a tundra rock field where lichens predominate, and an alpine tundra-meadow with herbs, grasses, sedges, rushes, mosses, and lichens. Tree line on Humphreys Peak, the highest summit of the San Francisco Peaks (shown to left), occurs at 11,000 to 11,400 ft. Snow-covered from late November to early April, the summit area receives from 33 to 40 inches of precipitation a year.
An interesting biogeographic note: Some 50 species of plants occur in the Arctic-Alpine Life Zone in Arizona. Forty percent of these are disjunct from the true tundra of the higher latitudes, and 15 of these are circumpolar in their distribution--meaning that they occur in Arctic areas of both Eurasia and North America. Only two plant species are endemic; one of these is a groundsel (an herb of the genus Senecio). Remember this biogeographic pattern when you look at and compare high alpine flora in the tropics.

Merriam's Life-zones


Desert grassland 

Over story: none

Blue grama (Bouteloua gracilis), galleta (Hilaria jamesii), and dropseeds (Sporobolus sp.) are common. Broom snakeweed (Gutierrezia sarothrae) occurs in most areas along with scattered big sagebrush (Artemisia tridentata) and one-seed juniper (Juniperus monosperma) on ridges and rocky areas


The Great Basin Desert Scrub plant community covers approximately 435,000 acres within FFO boundaries, 75,000 acres within AFO boundaries, and 200 acres on USFS land and dominates the landscape in the northwestern portion of the planning area. 

Over story: none

The major shrub species in this type are big sagebrush, shadscale (Atriplex confertifolia), greasewood (Sarcobatus vermiculatus), and fourwing saltbush (Atriplex canescens). Big sagebrush has increased dramatically over the past 125 years. Most areas now dominated by big sagebrush in New Mexico were grassland or savannah in the middle of the last century (Dick-Peddie 1993). Within Great Basin Desert Scrub, big sagebrush usually occurs at higher elevations than the saltbush communities. Other sagebrush species found with big sagebrush are black sage (Artemisia arbuscula) and Bigelow sage (A. bigelovii). Other shrub species found with saltbush include winterfat (Ceratoides lanata), rabbitbrush (Chrysothamnus sp.), and Nuttal’s saltbush (Atriplex nuttallii). Widespread grasses in this vegetation type include alkali sacaton (Sporobolus airoides), western wheatgrass (Agropyron smithii), Indian ricegrass (Oryzopsis hymenoides), and blue grama (Dick-Peddie 1993).


The Juniper Savannah plant community lies primarily in a band along the southern boundary of the planning area, and covers approximately 56,000 acres within FFO boundaries and 136,000 acres within AFO boundaries. This vegetation type occurs between the conifer woodlands and grasslands and has been expanding during this century due mainly to human activities, such as livestock grazing and fire suppression. This type consists of widely scattered low trees interspersed in grasslands. 

One-seed juniper and Utah juniper (Juniperus osteosperma) are typical, as are big sagebrush, Bigelow sagebrush, and shadscale. Blue grama, galleta, Indian ricegrass, and sideoats grama (Bouteloua curtipendula) are common grass species (Dick-Peddie 1993).


The Piñon-Juniper Woodland plant community type occurs primarily in the northeastern portion of the planning area and along the southern boundary. It covers an estimated 633,000 acres within FFO boundaries, 91,000 acres within AFO boundaries, 192,000 acres on USFS land, and 13,000 acres on USBR land. Trees in these woodlands can form a dense canopy or be fairly open. Dense stands generally occur above 6,600 feet in elevation and the dominant tree species are piñon (Pinus edulis), Utah juniper, Gambel’s oak (Quercus gambellii), and true mountain mahogany (Cercocarpus montanus), with occasional stringers of ponderosa pine (Pinus ponderosa). Common ground cover species are mutton grass (Poa fendleriana), western wheatgrass (Agropyron smithii), buckwheat (Eriogonum sp.), and penstemon (Penstemon sp.) (BLM 1997). More open stands are located on drier sites below 6,600 feet elevation where piñon, Utah juniper, big sagebrush and antelope bitterbush (Purshia tridentata) are common. Blue grama and galleta are the principal grass species. Relatively large stands of big sagebrush can occur within the open woodlands (BLM 1997).


The Ponderosa Pine Forest occurs principally on USFS land along the eastern boundary of the planning area, although there is a small amount on FFO land. There are an estimated 2,300 acres within FFO boundaries, 5,600 acres within AFO boundaries, and 43,300 acres on USFS land. This forest occurs on BLM land primarily in deep canyons on north and east facing slopes. Common tree species are ponderosa pine, piñon, and Douglas fir (Pseudotsuga menziesii). The shrub component is dominated by antelope bitterbush, true mountain mahogany, and Gambel’s oak with grass cover dominated by mutton grass and western wheatgrass. On the Jicarilla Ranger District and the Cuba Ranger District, this vegetation type occurs in scattered locations in deep canyons on north and east facing slopes. Dominant plant species at these locations are similar to those found on BLM lands.


The subalpine montane grasslands is represented by approximately 300 acres within FFO boundaries located on the very western side of the planning area along the New Mexico Arizona border. These grasslands are commonly found above 8,900 feet and up to 11,500 feet on relatively smooth terrain of southwestern exposures with slopes ranging from 20 to 50 percent (Dick-Peddie 1993). Dominant grasses in this vegetation unit include fescue (Festuca sp.), oatgrass (Danthonia sp.), tuft-hair grass (Deschampsia sp.), Junegrass (Koeleria sp.), bluegrass (Poa sp.), and muhly (Muhlenbergia sp.). Areas of heavy grazing experience vegetation community shifts from Thurber and Arizonia Fescue (Festuca thurberi and F. arizonica respectively), oatgrass and Junegrass to Kentucky bluegrass (Poa pratensis) (Dick-Peddie 1993). Restoration to a pregrazing state of native vegetation occurs within 2 to 4 years if adequate recovery is allowed (Dick-Peddie 1993). The subalpine coniferous forest unit occurs along the eastern boundary of the planning area with an estimated 6,700 acres of USFS land on the Santa Fe National Forest. The vegetation unit is characterized by elevations of approximately 9,500 feet to timberline, approximately 12,000 feet (Dick-Peddie 1993). Common flora include Englemann spruce (Picea englemanii), Douglas-fir, Juniper species, Corkbark fir (Abies lasiocarpa), currants (Ribes sp.), fringed brome (Bromus ciliatus), mountain trisetum (Trisetum spicatum), and bluegrass (Dick-Peddie 1993). Vegetation communities vary among different alpine regions due to elevation and moisture differences.


The urban, farmland, and open water unit includes federal, state and private lands in the northern tier of the planning area. This vegetation unit represents the non-native land cover according to Dick-Peddie (1993). Open water areas are permanently inundated in surface water, such as the Navajo Reservoir. Irrigated cropland represents the farmland located adjacent to the San Juan, Animas, La Plata, and Los Piñas Rivers in this vegetation unit. Urban areas are concentrated in the tricities area (Aztec, Bloomfield, and Farmington).

Invasive Weeds

Invasive plants are found in the San Juan Basin, particularly in areas disturbed by surface activities. These plants displace native plant communities and degrade wildlife habitat. A total of 212 invasive and poisonous weeds have been identified on FFO land (Heil and White 2000). Table 3-9 lists the invasive and non-native species of concern in the planning area and the current management classes for each species. The following management classes provide information on the current status of each species in the planning area and the priority for treatment:

• Class A: Non-native plants that have a limited distribution within or have not yet invaded the state. Some are found on public lands within the planning area, and preventing and eliminating infestations of these weeds has the highest priorities in the BLM management plan.

• Class B: Non-native plants that are presently limited to a particular part of the planning area. The management priorities are to contain them within their current areas and prevent new infestations.

• Class C: Non-native plants that are widespread throughout much of the public land within the planning area. Long-term programs of management and suppression are encouraged.


RIPARIAN AREAS AND WETLANDS

Riparian areas are defined by the BLM as “a form of wetland transition between permanently saturated wetlands and upland areas. These areas exhibit vegetation or physical characteristics reflective of permanent surface or subsurface water influence. Lands along, adjacent to, or contiguous with perennially and intermittent flowing rivers and streams, glacial potholes, and the shores of lakes and reservoirs with stable water levels are typical riparian areas” (Leonard et al. 1992). Wetlands are regulated by the U.S. Army Corps of Engineers (USACE) and defined as “those areas inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas” (US Army 1987).

Seventy riparian areas in 35 river tracts and along portions of nine ephemeral stream reaches were identified on FFO land as shown in Map 3-7 (BLM 2000b). Subsequently, 13 additional tracts along ephemeral drainages were identified. Riparian areas associated with the river tracts comprise 471 acres along 20 miles of river adjacent to the Animas, San Juan, and La Plata Rivers and Pump Canyon Creek (Table 3-10) (BLM 2000b). An estimated 1,042 acres of riparian vegetation occurs along an estimated 109 miles of ephemeral streams including Blanco Reach, Carrizo Canyon, Ditch Canyon, Gobernador Canyon, Kutz Canyon, La Jara Canyon, Largo Canyon, Palluche Canyon, and Simon Canyon (BLM 2000b). Wetlands include the 25 acres Carrizo Oxbow wetland identified in BLM (2000b) and the more recently identified 10 acre Desert Hills wetland. Common plant species in riparian areas on FFO land are cottonwoods (Populus spp.), willows (Salix spp.), saltcedar (Tamarix spp.), Russian olive (Elaeagnus angustifolia), sedges (Carex spp.), rushes (Juncus spp.), reed canarygrass (Phalaris arundinacea), cattails (Typha spp.), bulrushes (Scirpus spp.), alkali sacaton, galletagrass, Indian rice-grass, sagebrush, greasewood, and four-wing saltbush (BLM 2000b). Twenty riparian areas occur along 21 miles of the Rio Puerco, 18 miles of Arroyo Chico, and 3 miles of other ephemeral drainages, for a total of about 42 miles on AFO land (see Table 3-10). There are a total of 1,169 acres of riparian habitat along these drainages, with 601 acres along Arroyo Chico and 523 acres along Rio Puerco. Most of the native cottonwoods and willows have disappeared from these riparian areas and the invasive saltcedar and Russian olive are common in some areas.


Brown and Pase (1980) in their 1:1,000,000 map of Biotic Communities of the Southwest mapped five major "Biomes" for the Sevilleta as defined by Brown, Lowe and Pase (1979):

1. Plains and Great Basin Grassland (142.1) described as a mix of gramas (Bouteloua spp.), principally blue grama (B. gracilis) along with alkali sacaton (Sporobolus airoides), Indian ricegrass (Oryzopsis hymenoides).

2. Semidesert Grasslands (143.1), principally black grama (B. eriopoda).

3. Chihuahuan Desert Scrub (153.2) made up of a wide variety of desert shrubs, but principally referring to creosotebush (Larrea trientata).

4. Great Basin Conifer Woodland (122.4) represented by pinyon (Pinus edulis) and oneseed juniper (Juniperus monosperma).

5. Petran Montane Conifer Forest (122.3) represented by ponderosa pine (P. ponderosa)

A VEGETATION CLASSIFICATION AND MAP

1. Water or Wet Ground 

Water and wet ground of river, streams channels or tanks, with inclusions of barren or very sparsely vegetated ground. This unit is mostly associated with drainage bottoms of the Rio Salado, Rio Puerco and Rio Grande (1,400 û 1,500 m; 4,600-4,900 ft.). It may include some sparsely vegetated dunelands north of the Rio Salado confluence and some alluvial flats.

TM-1. Water and barren, probably wet disturbed ground

2. Barren or Sparsely Vegetated 

Over story: none

Open alluvial flats of basin bottoms (1,430 - 1,550 m; 4,700-5,090 ft) that are either barren or sparsely vegetated with alkali sacaton (Sporobolus airoides) and burrograss (Scleropogon brevifolius), or are barren hills (badlands).

TM-3. Sparse Grassland (Alkali Sacaton); alkali sacaton (Sporobolus airoides) and burrograss (Scleropogon brevifolius)
TM-2. Sparse Grassland (Black Grama or Galleta); barren disturbed ground

3. Great Basin Grasslands (Galleta and Indian Ricegrass Grasslands)

Over story: none

Sparse grasslands most often associated with lowland sandy soils (1,450-1,750 m; 4,750-5,750 ft). The Grasslands are usually dominated by species with Great Basin affinities such as galleta (Hilaria JamesiiI), Indian ricegrass (Oryzopsis hymenoides) and sand dropseed (Sporobolus cryptandrus). Where the unit extends up hillslopes, black grama (Bouteloua eriopoda) grasslands may occur. Shrubs or dwarf shrubs are often abundant in these grassland stands, and there are inclusions of fourwing saltbush (Atriplex canescens), broom dalea (Psorothamnus scoparius) and shadscale (Atriplex confertifolia) shrublands.

TM-4. Galleta or Black Grama Grasslands; Inclusion: Shadscale Shrubland
TM-8. Galleta or Sand Dropseed Grasslands
TM-12. Galleta or Burrograss Grasslands; Inclusion: Fourwing Saltbush Shrubland
TM-11. Indian Ricegrass or Black Grama Grasslands, or Broom Dalea Shrubland

4. Transition Chihuahuan and Great Basin Grasslands (Black Grama Grasslands with Galleta)

Over story: none

Grasslands associated with sandy to coarse loamy soils along the lower piedmont  (1,450-1,700m; 4,750-5,575 ft). They are typically dominated by black grama (Bouteloua eriopoda), a species with the center of its distribution in the southwest U.S. and northern Mexico. Galleta (Hilaria jamesii), a Great Basin Grassland indicator is an important associate, sometimes dominating stands along with mesa dropseed (Sporobolus flexuosus). Blue grama (B. gracilis) is also an important component of many stands, particularly along the upper elevation margins. On deeper sands, Plains-Mesa Microphyllous Sand Scrub dominated by sand sagebrush (Artemisia filifolia) may occur as a minor inclusion.

TM-9, 10 & 17. Black Grama Grassland; Inclusion: Galleta Grassland

5. Chihuahuan Desert Grasslands (Black Grama Grasslands) 

Over story: none

Grasslands dominated by black grama (Bouteloua eriopoda) and associated with alluvial piedmonts (bajadas) and foothills from low to mid-elevations (1,500-1,800m; 4,925-5,900 ft). Soils are typically loamy (sometimes sandy) and underlain by thick caliche layers (calcium carbonate accumulations). Purple threeawn (Aristida purpurea) grasslands can occur as a minor inclusion on more disturbed sites. Other common associates are blue grama (B. gracilis), featherplume (Dalea formosa), Torrey's jointfir (Ephedra torreyana), soapweed yucca (Yucca glauca) and woody crinklemat (Tequila canescens).

TM-5. Black Grama Grassland
TM-14. Black Grama Grassland; Inclusion: Purple Threeawn

6. Transition Chihuahuan and Plains Grassland (Black Gram Grasslands with Blue Grama)

Over story: none

Grasslands dominated by both black grama (Bouteloua eriopoda) and blue grama (B. gracilis), indicator species for Chihuahuan Desert Grasslands and Great Plains Grasslands, respectively. They occur primarily on alluvial piedmonts (bajadas) of the west side of the Sevilleta, but also to a limited degree in the foothills on both sides (1,500-1,800m; 4,925-5,900 ft). Soils are commonly sandy on the surface, but loamy with depth and underlain by caliche layers (calcium carbonate accumulations). Creosotebush (Larrea tridentata) shrublands can occur as a minor inclusion. Other common associates include the shrubs Torrey's jointfir (Ephedra torreyana), soapweed yucca (Yucca glauca) and broom snakeweed (Gutierrezia sarothrae); the grasses sand dropseed (Sporobolus crytandrus), burrograss (Scleropogon brevifolius) and purple threeawn (Aristida purpurea); and forbs such as mock vervain (Glandularia wrightii), desert marigold (Baileya multiradicata) and zinnia (Zinnia grandiflora).

TM-15. Black Grama Grassland; Inclusion Creosotebush Shrubland
TM-18. Black Grama or Blue Grama Grasslands
TM-19. Black Grama or Blue Grama Grasslands

7. Plains Grasslands (Blue Grama and Hairy Grama Grasslands) 

Over story: none

Grasslands dominated by blue grama (Bouteloua gracilis) with hairy grama as a common co-dominant (B. hirsuta), both common short-grass species of the Great Plains. They occur along upper piedmont slopes (bajadas), foothills and in mountain valleys (1,500-1,950m; 4,825-6,400 ft). Soils are often moderately well-developed with loamy to clayey textures and underlain by caliche layers (calcium carbonate accumulations). Giant Sacaton Grasslands occur as an inclusion in some valleys. Common associates include the shrubs winterfat (Krascheninnikovia lanata), fourwing saltbush (Atriplex canescens); the grasses black grama (B. eriopoda), sideoats grama (B. curtipendula) and dropseeds (Sporobolus contractus & S. cryptandrus); and forbs such as lacy tansyaster (Machaeranthera pinnatifida) and Douglas' groundsel (Senecio flacicidus var. douglasii).

TM-25. Blue Grama or Giant Sacaton Grasslands
TM-24. Blue Grama; Inclusions: Black Grama Grassland, Galleta Grassland or Sand Sage Shrubland

8. Chihuahuan or Great Basin Lowland/Swale Grasslands (Alkali or Giant Sacaton Grasslands)

Over story: none

Grasslands dominated by either the hummock-forming alkali sacaton (Sporobolus airoides) of Great Basin affinity, or the taller giant sacaton (S. wrightii) of Chihuahuan Desert affinity. Alkali sacaton grasslands often occur as large, monotypic stands of moderate cover on heavy clay soils in swales or alluvial flats of lowland valleys and basins (1,450-1,700m; 4,750-5,575 ft). Burrograss (Scleropogon brevifolius) can occur as a co-dominant along with scattered fourwing saltbush (Atriplex canescens). In contrast, giant sacaton forms tall and dense stands along lower-elevation drainageways of ephemeral streams (arroyos). Shrubs are uncommon or absent. Stands of Fourwing Saltbush Shrublands with understories dominated by alkali sacaton can occur as significant inclusions intermixed among the grasslands.

TM-29. Giant Sacaton Grassland
TM-20. Alkali Sacaton Grassland or Fourwing Saltbush Shrubland

9. Chihuahuan Desert Shrublands (Creosotebush)

Over story: none

Shrublands dominated by the evergreen creosote bush (Larrea tridentata), a widespread and characteristic evergreen shrub of the Chihuahuan Desert. Ground cover is sparse to well-represented by grasses such as black grama (Bouteloua eriopoda) or fluff grass (Erioneuron pulchellum). The shrublands occur on lower piedmonts (bajadas), foothills and alluvial flats (1,450-1,750m; 4,750-5,750 ft). Soils are relatively shallow and underlain by dense caliche layers (calcium carbonate accumulations that are sometimes exposed at the surface). They are commonly interspersed with Black Grama, Galleta (Hilaria jamesii) or Indian Ricegrass (Oryzopsis hymenoides) Grasslands. There are minor inclusions of Shadscale Shrubland and barrens areas, and, at upper elevations, Oneseed Juniper Woodlands. Other common associates include pricklyleaf dogweed (Thymophylla acerosa), Fendler's bladderpod (Lesquerella fendleri), and broom snakeweed (Gutierrezia sarothrae).

TM-13. Creosotebush Shrubland and Black Grama Grassland
TM-6. Creosote Shrubland, and Galleta or Indian Ricegrass Grasslands

Inclusion: Shadscale Shrubland or Barren Ground TM-21. Creosotebush Shrubland (in part see No. 11).

10. Great Basin Shrublands (Fourwing Saltbush or Broom Dalea)

Over story: none

Shrublands dominated by fourwing saltbush (Atriplex canescens), a widespread species with the center of their distribution in the Great Basin. They occur primarily on the west side on sandy deposits, alluvial flats of lowland valleys and, occasionally, on recent alluvial fan deposits (1,430-1,700m; 4,700-5,575 ft). Broom dalea (Psorothamnus scoparius), a Chihuahuan element may also be abundant and mixed in with the saltbush. Where the sands are particularly deep, coppice dunes can form around stems of the broom dalea. Understories are either barren or dominated by grasses. On alluvial flats alkali sacaton (S. airoides) is the common dominant. Sandier sites are characterized by scattered grasses and forbs such as dropseeds (Sporobolus flexulosus, S. cryptandrus, S. contractus and S. gigantea), desert marigold (Baileya multiradicata), and spectaclepod (Dimorphocarpa wislizeni). There are occasional inclusions of disturbed sites dominated by threeawn grasses (Aristida spp.).

TM-7. Broom Dalea Shrubland
TM-16. Fourwing Saltbush or Honey Mesquite or Broom Dalea Shrubland
TM-22. Fourwing Saltbush Shrubland; Inclusion: Threeawn Grassland

11. Rocky Mountain Conifer Savanna (Oneseed Juniper Woodlands) 

Very open woodlands of lower elevation foothills, escarpments, and piedmonts (bajadas) and alluvial fans (1,550-2,100m; 5,100-6,900 ft). Stands are characterized by scattered, low-statured oneseed juniper (Juniperus monosperma) trees with the grassy inter-tree spaces dominated by grama grasses (Bouteloua gracilis, B. hirsuta, B. eriopoda, and B. curtipendula). Pinyon pines (Pinus edulis) are sub-dominant or absent. Stands are often intermixed at the lower elevations with patches of Blue or Black Grama Grasslands, and Shrub Live Oak Shrublands at higher elevations. Shrub live oak stands are particularly prominent on escarpment slopes of the Los Pinos Mountains. Diversity can be moderately high, and common associates are the shrubs banana yucca (Yucca bacata), broom snakeweed (Gutierrezia sarothrae), tree cholla (Opuntia imbricata), and tulip pricklypear (O. phaeacantha); the grasses New Mexico needlegrass (Stipa neomexicana), galleta (Hilaria jamesii) and purple threeawn (Aristida purpurea); and a wide variety of forbs such as plains blackfoot (Melapodium leucanthum) and zinnia (Zinnia grandiflora).

TM-23. Oneseed Juniper Woodland Savanna; Inclusion: Blue Grama Grassland
TM-26. Oneseed Juniper Woodland, or Shrub Live Oak Shrubland, or Black Grama or

Blue Grama Grasslands TM-28. Oneseed Juniper Woodland, or Shrub Live Oak Shrubland
TM-21. Oneseed Juniper Woodland (in part, see No.9)

12. Rocky Mountain Conifer Woodlands (Pinyon Woodlands)

Open to moderately closed woodlands dominated by low-statured pinyon pine (Pinus edulis) with oneseed juniper (Juniperus monosperma) as sub-dominant associate. These woodlands are associated with moderate to steep slopes of the highest elevations of the Los Pinos and Ladrones Mountains (1,850-2,300; 6,050-7,550 ft). Understories are a mixture of shrubs and scattered grasses and forbs. Shrub live oak (Quercus turbinella), mountain mahogany (Cercocarpus montanus), banana yucca (Yucca bacata) and sacuahista (Nolinia microcarpa) are often well represented to abundant. Sideoats grama (Bouteloua curtipendula), blue grama (B. gracilis), and wolfstail (Lycurus phleoides) are the most common grasses. Forb diversity can be moderate to high; ragleaf bahia (Bahia dissecta), false pennyroyal (Hedeoma nana) and Fendler's sandmat (Chamaesyce fendleri) are common. Inclusions of mountain mahogany stands occur on rugged escarpment slopes and commonly on sites that have been burned. Near the summit of the Ladrones there are small inclusions of Ponderosa Pine (Pinus ponderosa var. scopulorum) Woodland.

TM-27. Pinyon or Oneseed Juniper Woodlands; Inclusions of Mountain Mahogany Shrubland and Sideoats Grama Grassland

TM-31. Pinyon Woodland

13. Rio Grande Riparian Woodlands (Rio Grande Cottonwood and Salt Cedar Riparian Woodland)

These are riparian woodlands or forested wetlands that occur along river bars and terraces of the Rio Grande, Rio Puerco and Rio Salado drainages (1,430-1,550m; 4,700-5,100 ft). They range from open canopied woodlands of the native Rio Grande Cottonwood (Populus deltoides var. wislizeni) with grassy understories of alkali sacaton (Sporobolus airoides), inland saltgrass (Distichlis spicata) or vine mesquite grass (Panicum obtusum), to dense, shrub-like stands of the introduced salt cedar (Tamarix ramosissima) with little or no understory.

TM-30. Salt Cedar Woodland or Fourwing Saltbush Shrubland
TM-32. Salt Cedar or Rio Grande Cottonwood Woodland

A VEGETATION CLASSIFICATION AND MAP

UPLAND VEGETATION

Public lands in San Juan, McKinley, Rio

Arriba, and Sandoval Counties support a

diversity of upland and riparian plant communities.

These plant communities or vegetation

types are controlled in large part by site-specific

topography, soil type, and climatic conditions.

The planning area contains five major

vegetation units, as well as the non-native cover

type represented by urban/agricultural areas,

shown in Map 3-6 (Dick-Peddie 1993).

 

An estimated 223,600 acres of desert

grasslands are found within FFO boundaries,

65,500 acres are on AFO land, and 11,800

acres on USFS land (Table 3-8). There are

large tracts of desert grassland vegetation

throughout the central portion of the planning

area. Blue grama (Bouteloua gracilis), galleta

(Hilaria jamesii), and dropseeds (Sporobolus sp.) are common. Broom snakeweed

(Gutierrezia sarothrae) occurs in most areas

along with scattered big sagebrush (Artemisia tridentata) and one-seed juniper (Juniperus monosperma) on ridges and rocky areas (BLM

1988).

 

The Great Basin Desert Scrub plant

community covers approximately 435,000

acres within FFO boundaries, 75,000 acres

within AFO boundaries, and 200 acres on

USFS land and dominates the landscape in

the northwestern portion of the planning area.

The major shrub species in this type are big

sagebrush, shadscale (Atriplex confertifolia),

greasewood (Sarcobatus vermiculatus), and

fourwing saltbush (Atriplex canescens). Big

sagebrush has increased dramatically over the

past 125 years. Most areas now dominated by

big sagebrush in New Mexico were grassland

or savannah in the middle of the last century

(Dick-Peddie 1993). Within Great Basin

Desert Scrub, big sagebrush usually occurs at

higher elevations than the saltbush communities.

Other sagebrush species found with big

sagebrush are black sage (Artemisia arbuscula) and Bigelow sage (A. bigelovii).

Other shrub species found with saltbush

include winterfat (Ceratoides lanata), rabbitbrush

(Chrysothamnus sp.), and Nuttal’s

saltbush (Atriplex nuttallii). Widespread

grasses in this vegetation type include alkali

sacaton (Sporobolus airoides), western wheatgrass

(Agropyron smithii), Indian ricegrass

(Oryzopsis hymenoides), and blue grama

(Dick-Peddie 1993).

 

The Juniper Savannah plant community

lies primarily in a band along the southern

boundary of the planning area, and covers

approximately 56,000 acres within FFO

boundaries and 136,000 acres within AFO

boundaries. This vegetation type occurs

between the conifer woodlands and grasslands

and has been expanding during this century

due mainly to human activities, such as

livestock grazing and fire suppression. This type

consists of widely scattered low trees

interspersed in grasslands. One-seed juniper

and Utah juniper (Juniperus osteosperma) are

typical, as are big sagebrush, Bigelow

sagebrush, and shadscale. Blue grama, galleta,

Indian ricegrass, and sideoats grama

(Bouteloua curtipendula) are common grass

species (Dick-Peddie 1993).

The Piñon-Juniper Woodland plant

community type occurs primarily in the

northeastern portion of the planning area and

along the southern boundary. It covers an

estimated 633,000 acres within FFO

boundaries, 91,000 acres within AFO

boundaries, 192,000 acres on USFS land, and

13,000 acres on USBR land. Trees in these

woodlands can form a dense canopy or be

fairly open. Dense stands generally occur above

6,600 feet in elevation and the dominant tree

species are piñon (Pinus edulis), Utah juniper,

Gambel’s oak (Quercus gambellii), and true

mountain mahogany (Cercocarpus montanus),

with occasional stringers of ponderosa pine

(Pinus ponderosa). Common ground cover

species are mutton grass (Poa fendleriana),

western wheatgrass (Agropyron smithii),

buckwheat (Eriogonum sp.), and penstemon

(Penstemon sp.) (BLM 1997). More open

stands are located on drier sites below 6,600

feet elevation where piñon, Utah juniper, big

sagebrush and antelope bitterbush (Purshia tridentata) are common. Blue grama and

galleta are the principal grass species. Relatively

large stands of big sagebrush can occur within

the open woodlands (BLM 1997).

The Ponderosa Pine Forest occurs

principally on USFS land along the eastern

boundary of the planning area, although there

is a small amount on FFO land. There are an

estimated 2,300 acres within FFO boundaries,

5,600 acres within AFO boundaries, and

43,300 acres on USFS land. This forest occurs

on BLM land primarily in deep canyons on

north and east facing slopes. Common tree

species are ponderosa pine, piñon, and

Douglas fir (Pseudotsuga menziesii). The shrub

component is dominated by antelope

bitterbush, true mountain mahogany, and

Gambel’s oak with grass cover dominated by

mutton grass and western wheatgrass. On the

Jicarilla Ranger District and the Cuba Ranger

District, this vegetation type occurs in scattered

locations in deep canyons on north and east

facing slopes. Dominant plant species at these

locations are similar to those found on BLM

lands.

The subalpine montane grasslands is

represented by approximately 300 acres within

FFO boundaries located on the very western

side of the planning area along the New Mexico

Arizona border. These grasslands are

commonly found above 8,900 feet and up to

11,500 feet on relatively smooth terrain of

southwestern exposures with slopes ranging

from 20 to 50 percent (Dick-Peddie 1993).

Dominant grasses in this vegetation unit include

fescue (Festuca sp.), oatgrass (Danthonia sp.),

tuft-hair grass (Deschampsia sp.), Junegrass

(Koeleria sp.), bluegrass (Poa sp.), and muhly

(Muhlenbergia sp.). Areas of heavy grazing

experience vegetation community shifts from

Thurber and Arizonia Fescue (Festuca thurberi

and F. arizonica respectively), oatgrass and

Junegrass to Kentucky bluegrass (Poa pratensis)

(Dick-Peddie 1993). Restoration to a pregrazing

state of native vegetation occurs within

2 to 4 years if adequate recovery is allowed

(Dick-Peddie 1993).

The subalpine coniferous forest unit occurs

along the eastern boundary of the planning

area with an estimated 6,700 acres of USFS

land on the Santa Fe National Forest. The

vegetation unit is characterized by elevations of

approximately 9,500 feet to timberline,

approximately 12,000 feet (Dick-Peddie 1993).

Common flora include Englemann spruce

 

(Picea englemanii), Douglas-fir, Juniper species,

Corkbark fir (Abies lasiocarpa), currants (Ribes

sp.), fringed brome (Bromus ciliatus), mountain

trisetum (Trisetum spicatum), and bluegrass

(Dick-Peddie 1993). Vegetation communities

vary among different alpine regions due to

elevation and moisture differences.

The urban, farmland, and open water unit

includes federal, state and private lands in the

northern tier of the planning area. This

vegetation unit represents the non-native land

cover according to Dick-Peddie (1993). Open

water areas are permanently inundated in

surface water, such as the Navajo Reservoir.

Irrigated cropland represents the farmland

located adjacent to the San Juan, Animas, La

Plata, and Los Piñas Rivers in this vegetation

unit. Urban areas are concentrated in the tricities

area (Aztec, Bloomfield, and Farmington).

Invasive Weeds

Invasive plants are found in the San Juan

Basin, particularly in areas disturbed by surface

activities. These plants displace native plant

communities and degrade wildlife habitat. A

total of 212 invasive and poisonous weeds

have been identified on FFO land (Heil and

White 2000). Table 3-9 lists the invasive and

non-native species of concern in the planning

area and the current management classes for

each species. The following management

classes provide information on the current

status of each species in the planning area and

the priority for treatment:

• Class A: Non-native plants that have a

limited distribution within or have not

yet invaded the state. Some are found

on public lands within the planning

area, and preventing and eliminating

infestations of these weeds has the

highest priorities in the BLM

management plan.

• Class B: Non-native plants that are

presently limited to a particular part of

the planning area. The management

priorities are to contain them within

their current areas and prevent new

infestations.

• Class C: Non-native plants that are

widespread throughout much of the

public land within the planning area.

Long-term programs of management

and suppression are encouraged.

 

RIPARIAN AREAS AND WETLANDS

Riparian areas are defined by the BLM as

“a form of wetland transition between

permanently saturated wetlands and upland

areas. These areas exhibit vegetation or

physical characteristics reflective of permanent

surface or subsurface water influence. Lands

along, adjacent to, or contiguous with

perennially and intermittent flowing rivers and

streams, glacial potholes, and the shores of

lakes and reservoirs with stable water levels are

typical riparian areas” (Leonard et al. 1992).

Wetlands are regulated by the U.S. Army Corps

of Engineers (USACE) and defined as “those

areas inundated or saturated by surface or

ground water at a frequency and duration

sufficient to support, and that under normal

circumstances do support, a prevalence of

vegetation typically adapted for life in saturated

soil conditions. Wetlands generally include

swamps, marshes, bogs, and similar areas” (US

Army 1987).

Seventy riparian areas in 35 river tracts and

along portions of nine ephemeral stream

reaches were identified on FFO land as shown

in Map 3-7 (BLM 2000b). Subsequently, 13

additional tracts along ephemeral drainages

were identified. Riparian areas associated with

the river tracts comprise 471 acres along 20

miles of river adjacent to the Animas, San Juan,

and La Plata Rivers and Pump Canyon Creek

(Table 3-10) (BLM 2000b). An estimated

1,042 acres of riparian vegetation occurs along

an estimated 109 miles of ephemeral streams

including Blanco Reach, Carrizo Canyon, Ditch

Canyon, Gobernador Canyon, Kutz Canyon,

La Jara Canyon, Largo Canyon, Palluche

Canyon, and Simon Canyon (BLM 2000b).

Wetlands include the 25 acres Carrizo Oxbow

wetland identified in BLM (2000b) and the

more recently identified 10 acre Desert Hills

wetland. Common plant species in riparian

areas on FFO land are cottonwoods (Populus spp.), willows (Salix spp.), saltcedar (Tamarix spp.), Russian olive (Elaeagnus angustifolia),

sedges (Carex spp.), rushes (Juncus spp.), reed

canarygrass (Phalaris arundinacea), cattails

(Typha spp.), bulrushes (Scirpus spp.), alkali

sacaton, galletagrass, Indian rice-grass,

sagebrush, greasewood, and four-wing saltbush

(BLM 2000b).

Twenty riparian areas occur along 21 miles

of the Rio Puerco, 18 miles of Arroyo Chico,

and 3 miles of other ephemeral drainages, for a

total of about 42 miles on AFO land (see Table

3-10). There are a total of 1,169 acres of

riparian habitat along these drainages, with 601

acres along Arroyo Chico and 523 acres along

Rio Puerco. Most of the native cottonwoods

and willows have disappeared from these

riparian areas and the invasive saltcedar and

Russian olive are common in some areas.

Upland plants, such as rabbitbrush, have

moved into some of the riparian areas.

However, native vegetation is evident and

increasing in some areas due to the exclusion of

livestock or limitations on grazing. Vegetation in

these areas typically grows in zones from wetter

to dryer, starting with sedges and rushes

common in the wettest zone and willows,

grasses, saltcedar, rabbitbrush, and salt grass

growing in progressively dryer areas. A few

scattered remnant cottonwoods are present

(BLM 2000c).

Proper-functioning condition (PFC) surveys

were first conducted on FFO lands in 1994.

During 1994, surveys took place on 3 tracts of

the San Juan River, 9 tracts of the La Plata

River, and the BLM portions of Largo Canyon,

Carrizo Canyon, Palluche Canyon, La Jara

Canyon, Gobernador Canyon, Kutz canyon,

Pump Canyon Ditch Canyon, Blanco Canyon,

and Simon Canyon. Of the river tracts, 2 were

rated as PFC, 3 were rated as functioning at

risk (FAR) with an upward trend, 6 were rated

as FAR with no apparent trend, and 1 was

rated as non-functional (NF). Of the

intermittent and ephemeral systems, 1 was

rated as PFC, 10 were rated as FAR with an

upward trend, 6 were rated as FAR with no

apparent trend, 2 were rated as FAR with

downward trend, and 15 were rated NF. All of

 

Vegetation Type community Life Zone Over Story Under Story
spruce fir forest  forest  Hudsonian Common flora include Englemann spruce (Picea englemanii), Douglas-fir, Juniper species, Corkbark fir (Abies lasiocarpa), currants (Ribes sp.), fringed brome (Bromus ciliatus), mountain trisetum (Trisetum spicatum), and bluegrass 
mixed conifer forest  forest  Canadian Douglas-fir, white fir, and blue spruce (Picea pungens)  Ponderosa pine, southwestern white pine, aspen.  currants (Ribes sp.), fringed brome (Bromus ciliatus), mountain trisetum (Trisetum spicatum), and bluegrass 
aspen forest  forest  Transition aspen  currants (Ribes sp.), fringed brome (Bromus ciliatus), mountain trisetum (Trisetum spicatum), and bluegrass 
ponderosa pine forest  forest  Transition ponderosa pine currants (Ribes sp.), fringed brome (Bromus ciliatus), mountain trisetum (Trisetum spicatum), and bluegrass 
juniper savannah woodland  woodland  Upper Sonoran One-seed juniper and Utah juniper (Juniperus osteosperma big sagebrush, Bigelow sagebrush, shadscale. blue grama, galleta, Indian ricegrass, and sideoats grama (Bouteloua curtipendula)
piñon juniper woodland  woodland  Upper Sonoran

piñon (Pinus edulis), Utah juniper, Gambel’s oak (Quercus gambellii), and true mountain mahogany (Cercocarpus montanus), with occasional stringers of ponderosa pine (Pinus ponderosa). 

 

mutton grass (Poa fendleriana), western wheatgrass (Agropyron smithii), buckwheat (Eriogonum sp.), and penstemon (Penstemon sp.

big sagebrush and antelope bitterbush (Purshia tridentata

blue grama and galleta (Hilaria jamesii)

grassland grassland Upper Sonoran none

common: Blue grama (Bouteloua gracilis), galleta (Hilaria jamesii), and dropseeds (Sporobolus sp.) Broom snakeweed (Gutierrezia sarothrae

grassland with big sagebrush juniper 

grassland Upper Sonoran none common: Blue grama (Bouteloua gracilis), galleta (Hilaria jamesii), and dropseeds (Sporobolus sp.) Broom snakeweed (Gutierrezia sarothrae

big sagebrush (Artemisia tridentata) and one-seed juniper (Juniperus monosperma) on ridges and rocky areas

subalpine montane grasslands 

grassland Canadian none 

above 8,900 feet and up to 11,500 feet on relatively smooth terrain of southwestern exposures with slopes ranging from 20 to 50 percent (Dick-Peddie 1993). 

USFS land on the Santa Fe National Forest. The vegetation unit is characterized by elevations of approximately 9,500 feet to timberline, approximately 12,000 feet (Dick-Peddie 1993).  

Common flora include Englemann spruce (Picea englemanii), Douglas-fir, Juniper species, Corkbark fir (Abies lasiocarpa),

fescue (Festuca sp.), oatgrass (Danthonia sp.), tuft-hair grass (Deschampsia sp.), Junegrass (Koeleria sp.), bluegrass (Poa sp.), and muhly (Muhlenbergia sp.). 

heavy grazing shifts from Thurber and Arizonia Fescue (Festuca thurberi and F. arizonica), oatgrass and Junegrass to Kentucky bluegrass (Poa pratensis

currants (Ribes sp.), fringed brome (Bromus ciliatus), mountain trisetum (Trisetum spicatum), and bluegrass 

scrubland big sagebrush

scrubland  Upper Sonoran none

big sagebrush, shadscale (Atriplex confertifolia), greasewood (Sarcobatus vermiculatus), fourwing saltbush (Atriplex canescens)

also black sage (Artemisia arbuscula), Bigelow sage (A. bigelovii).

grasses: alkali sacaton (Sporobolus airoides), western wheatgrass (Agropyron smithii), Indian ricegrass (Oryzopsis hymenoides), and blue grama 

Great Basin desert scrub saltbush 

desert scrubland   Upper Sonoran none

Saltbush 

also winterfat (Ceratoides lanata), rabbitbrush (Chrysothamnus sp.), and Nuttal’s saltbush (Atriplex nuttallii). 

grasses: alkali sacaton (Sporobolus airoides), western wheatgrass (Agropyron smithii), Indian ricegrass (Oryzopsis hymenoides), and blue grama

Riparian areas and wetlands marshland  Upper Sonoran cottonwoods (Populus spp.), willows (Salix spp.),

Russian olive (Elaeagnus angustifolia),

  saltcedar (Tamarix spp.),  sedges (Carex spp.), rushes (Juncus spp.), reed canarygrass (Phalaris arundinacea), cattails (Typha spp.), bulrushes (Scirpus spp.), alkali sacaton, galletagrass, Indian rice-grass, sagebrush, greasewood, and four-wing saltbush 

The urban, farmland, and open water unit 

other Upper Sonoran none
badlands  badlands  Upper Sonoran none alkali sacaton (Sporobolus airoides) and burrograss (Scleropogon brevifolius)

Forest 

The Ponderosa Pine Forest

Mixed Conifer

Spruce–Fir

Aspen